Providing Quality of Service in wireless networks might be considered to be oxymoronic. The channels used in such networks are not reliable when compared with traditional wired LANs due to range loss, interference from other wireless networks, and other sources of electromagnetic radiation etc. The term “Quality of Service” as used herein may be understood to be the transmission of data subject to meeting certain defined objectives for latency, jitter, throughput, and error rate, i.e., the rate at which packets are dropped.
As innovations in modulation and coding have provided more reliable communication at higher data rates, the possibility of the provision of QoS for wireless networks becomes feasible. The IEEE 802.11e Task Group of the IEEE 802.11 Wireless LAN Working Group has proposed QoS expansions to the 802.11 standard. Such QoS in wireless LAN will allow this standard to make the transmission of audio visual (AV) content using this technology feasible for the home network. Toward this end, this invention describes a scheduling algorithm that will be employed to schedule transmissions over the air in a manner suitable for meeting AV application requirements.
U.S. Pat. No. 6,262,980 to Leung et al., granted Jul. 17, 2001, for Dynamic resource allocation method and apparatus for broadband services in a wireless communications system describes a scheduling algorithm to coordinate the transmission of a number of base stations in a wireless network, but does not teach or suggest how to achieve QoS objectives of latency, jitter, and bandwidth for real-time AV transmission.
U.S. Pat. No. 6,229,795 to Pankaj et al., granted May 8, 2001, for System for allocating resources in a communication system, describes a contention-based allocation of resources.
U.S. Pat. No. 6,157,614 to Pasternak et al., granted Dec. 5, 2000, for Wireless ATM network with high quality of service scheduling, describes a wireless ATM network using per-VC scheduling.
U.S. Pat. No. 6,094,426 to Hokosalo et al., granted Jul. 25, 2000, for Method for scheduling packet data transmission, describes a soft-handoff technique.
U.S. Pat. No. 6,049,549 for Adaptive media control to Ganz et al., granted Apr. 11, 2000, describes a QoS application in a wireless LAN.
U.S. Pat. No. 5,638,371 to Raychaudhuri et al., granted Jun. 10, 1997, for Multiservices medium access control protocol for wireless ATM system describes a control system for a strict TDMA network.
Subnet Bandwidth Manager (SBM) RFC2814: A Protocol for RSVP-based Admission Control V. IEEE 802-style networks, located at http://www.ietf.org/rfc/rfc2814.txt, defines a specification for interaction of SBM clients, however, it does not teach how to schedule transmission opportunities from a stoichioastic or point-coordinated multiple access system.
The use of Resources ReSerVation Protocol (RSVP) with Integrated Services RFC2210, located at http://www.ietf.org/rfc/rfc2210.txt, is described in this Internet Engineering Task Force (IETF) specification, and determines what information elements are sent between RSVP clients to maintain QoS, and describes the information that is passed between bandwidth management entities. The reference does not teach how to implement a policy based on the information.
A. Mok, et al., Real-Time Scheduling of Multimedia Tasks, TR-98-14, located at http://www.cs.utexas.edu/users/UTCS/techreports/index/html/Abstracts.1998.html, describes a technique for determining whether or not a particular task can be scheduled at all over a network.
It further discusses a polling policy based on monitoring data transmission including retransmission statistics, and assigning communication resources includes adjusting data rate requirements in accordance with the collected retransmission statistics. This reference does not describe adaptation of periods for missed polls, nor does it provide a definition of a polling policy to distribute polls and transmit opportunities uniformly on a transmission period.